In terms of functional reconfiguration dimensions [77], textile reconfigurable antennas can be primarily classified into frequency reconfiguration [20,21,23,78], polarization reconfiguration, radiation pattern reconfiguration [79–82], and hybrid-mode reconfiguration [83,84]. Among these, operating frequency is the most critical parameter in antenna design, as it plays a central role in defining the physical dimensions and applicable scenarios of the antenna. Conventional passive antennas, constrained by their fixed frequency response characteristics, may not fully meet the stringent requirements of contemporary wireless communication systems. Frequency-reconfigurable antennas have attracted significant research interest due to their ability to dynamically adapt to different communication frequency bands. They are typically achieved by employing RF switches or varactor diodes to modulate the antenna’s resonant length or reactance, and utilizing mechanical or electrical tuning methods to alter the dielectric constant of antennas [85]. These mechanisms enable the antenna to exhibit either discrete or continuous frequency tunability within a specific bandwidth. In recent years, textile frequency-reconfigurable antennas have shifted the primary research focus to reconfigurable designs and composite material designs that combine conductive textiles with polymer substrates or integrate copper foils with fabric bases, thereby maintaining high dielectric constants in the substrate materials while achieving high conductivity in the radiating elements [84,86]. To achieve robust integration of textiles and electronic components, Simorangkir et al. [23] proposed using conductive fabric as the radiating element and ground plane of the antenna, co-integrating them with active components on a polydimethylsiloxane (PDMS)-based substrate, followed by PDMS encapsulation to fabricate a frequency-reconfigurable antenna (Fig. 3A). As depicted in Fig. 3B and C, by applying bias voltage to varactor diodes via a Bias Tee, the antenna achieved frequency tunability from 2.3 to 2.68 GHz. Experimental results demonstrated that this robust fabrication method maintained excellent impedance matching even when the antenna was bent on different parts of the human body or after washing. In another study focusing on wearability comfort and multi-band operation, Tahir and Javed [78] developed a frequency-reconfigurable antenna using a flexible denim substrate. By incorporating a single PIN diode controlled via a simple bias circuit, the antenna’s electrical length was altered, enabling dynamic switching between 2.45 and 5 GHz. The reliability of the antenna was further validated under on-body conditions. Nevertheless, these antenna designs that directly integrate varactor or PIN diodes still face practical challenges, such as discontinuous frequency-tuning capability and a restricted frequency-tuning range. To achieve more flexible control, Fumeaux’s research group [20] proposed an innovative modular design paradigm for textile antennas. Their approach involved developing a dedicated coplanar reconfiguration module integrating varactor diodes, bias circuits, and matching networks using standard FPCB fabrication techniques, establishing reliable interconnections between the rigid module and flexible textile substrate through snap-button coupling mechanisms. This architecture demonstrated significant performance advantages when applying controlled reverse bias voltage to strategically placed varactor diodes along the patch edge. The textile antenna achieved discrete tuning ranges of 32.8% (4.5 GHz) and 8.8% (5.8 GHz) while maintaining robust mechanical integration between electronic components and textile. The study effectively resolved the critical trade-off between frequency-tuning capability governed by electronic components and structural flexibility determined by textile substrates in wearable antenna design. To further expand the frequency-tuning range, the above research team adopted a similar fabrication strategy to develop an ultra-wideband tunable textile antenna [21]. As illustrated in Fig. 3D and E, the antenna’s radiating patch, microstrip feedline, ground plane, and shorting plane were constructed using silver-coated nylon rip-stop fabric, while the dual-layer dielectric substrate was made from Cumming Microwave PF4 foam. By incorporating a coplanar reconfiguration module into a planar inverted-F antenna (PIFA) structure, the tuning circuit allowed varactor capacitance values to be adjusted from 0.1 to 5 pF via bias voltage control to achieve a continuous transition between quarter-wave PIFA mode and half-wave patch mode, ultimately realizing an impressive 70% frequency-tuning range from 1.82 to 3.79 GHz.

The polarization characteristics of EM waves describe the oscillation pattern of the electric field vector along the propagation direction. Optimal signal transmission efficiency is achieved when the polarization states of the transmitting and receiving antennas are matched. Traditional polarization control primarily relies on manipulating the surface current distribution of the antenna to alter the spatial orientation or rotational behavior of the radiated electric field [67–69]. With the advancement of high-frequency communication systems, there is a growing demand for simultaneous frequency agility and polarization matching, giving rise to frequency and polarization-reconfigurable textile antenna technology. This technology holds significant value in improving spectral efficiency and enhancing anti-interference capabilities. Salleh et al. [84] developed a fully textile-based dual-reconfigurable (frequency and polarization) antenna. The design employs a truncated patch structure to achieve circular polarization, while frequency tuning is realized by adjusting the position of slots in the ground plane. Three PIN diodes are integrated into the ground plane slots, enabling dynamic control of the effective slot length through bias voltage. Additionally, 12 direct current (DC)-blocking capacitors are placed beneath the slots to ensure RF current flow while preventing DC interference. Experimental results demonstrate that the antenna can achieve flexible switching between 1.575 GHz (circular polarization) and 2.45 GHz (linear polarization).

The radiation pattern, characterizing the spatial distribution of antenna radiation energy, critically determines key performance metrics including coverage range, gain, and interference immunity. Dynamic pattern reconfiguration has become increasingly important for wearable RF systems to achieve adaptive communication coverage and target tracking. Current pattern-reconfiguration approaches primarily involve multi-feed excitation with dynamic phase control [87,88], integration of RF switches to manipulate current distribution [70,71], or mechanical deformation of antenna structures. Pattern reconfiguration typically requires overlapping multiple resonant modes, which significantly increases structural complexity and presents nontrivial fabrication challenges for textile-based implementations. Recent developments of pattern-reconfigurable textile antennas [79–82] have demonstrated innovative solutions to achieve pattern reconfigurability while maintaining wearability. Yan and Vandenbosch [81] proposed a 2.45-GHz textile antenna using felt substrate and conductive fabric, incorporating 6 PIN diodes along the patch edges to control via states. When diodes are forward-biased, the vias establish low-impedance connections to ground, forming an inductor–capacitor (LC) resonant network with the patch’s inherent capacitance to excite zeroth-order resonance (ZOR) mode, producing monopole-like omnidirectional radiation. With diodes in the off-state, the antenna operates in the +1 resonance mode. This metamaterial-inspired design enables flexible pattern switching at a fixed frequency through dispersion engineering of the transmission line characteristics. Similarly, a complementary approach by Mohamadzade et al. [79] employed a PDMS-conductive fabric composite to fabricate a circular patch antenna (Fig. 4A). Four PIN diodes are integrated on the radiating patch with DC bias lines embedded in the ground plane. Selective activation of these diodes perturbs the balanced radial current distribution, enabling reconfiguration between the TM02-mode monopole-like pattern and broadside radiation (Fig. 4B). While these designs successfully demonstrate stable dual-mode operation in wearable environments, PIN diode-based implementations suffer from notable limitations, including significant insertion loss in the conducting state and limited power handling capacity. To address these issues, Fumeaux’s research group [80] developed a radiation pattern-reconfigurable textile antenna by integrating RF-switch integrated circuits (ICs) (Fig. 4C). The antenna was fabricated using a PF-4 foam substrate combined with conductive fabric, where 2 button-style switches containing embedded RF-switch ICs were mounted on the textile patch and connected to the ground plane through via holes. As demonstrated in Fig. 4D, in the switch-off state, the RF-switch functions as a parallel circuit between capacitors and resistors, effectively disconnecting the patch from the ground plane and resulting in a broadside radiation pattern similar to that of a conventional half-wave patch antenna. In the switch-on state, the RF switch exhibits extremely low resistance, transforming the radiation pattern into an omnidirectional mode characteristic of monopole antennas by applying a bias voltage. This innovative design effectively addresses the limitations of PIN diode-based approaches while maintaining the flexibility required for wearable applications.

The performance of wearable antennas is significantly compromised by mechanical deformations and environmental variations. To address these challenges while achieving universal communication capability for both on-body and off-body scenarios, as well as maintaining stable operation under deformation and positional changes, researchers have developed sophisticated multi-modal reconfigurable textile antennas. These advanced systems integrate multidimensional control of frequency, polarization, and radiation pattern, enabling adaptive multifunctional operation in complex EM environments. Fumeaux’s research group [83] used the processing method and near-field coupling feeding method of the aforementioned integrated conductive fabric with the reconfigurable modules on the PF-4 foam substrate, and achieved multidimensional control by regulating the varactor diodes of the 3 reconfigurable modules (Fig. 4E). Firstly, they demonstrated a frequency and textile pattern-reconfigurable antenna capable of switching between edge-radiating and dipole-like modes with impressive frequency-tuning ranges of 57.3% and 27.2% for each radiation mode, respectively (Fig. 4F). Secondly, they demonstrated a frequency and polarization-reconfigurable textile antenna offering a 31.9% frequency-tuning range while maintaining linear polarization reconfigurability at 0°, 120°, or 240° orientations. This work represents an advancement from their earlier single-function reconfigurable textile antennas, achieved through the strategic integration of additional reconfigurable modules to realize more complex, multi-parameter adaptive control in practical wearable applications.

Textile-based active antennas for energy conversion primarily focus on rectifying antennas (rectennas) [32,89–94]. With advancements in flexible wearable technologies, there is a growing demand for battery-free active devices to enable more comfortable wearing experiences and enhanced safety. In today’s IoT-rich spectrum environment, RF energy harvesting demonstrates broader applicability across all temporal and environmental conditions compared to traditional energy solutions. Consequently, textile-based RF systems utilizing RF energy harvesting have become a key research focus. The core component determining energy conversion efficiency is the rectenna, which performs the critical function of converting RF energy into DC power. A rectenna system consists of 2 essential parts: an energy-capturing antenna and a rectifier circuit with high-frequency filtering capabilities. The performance of rectennas depends not only on the radiation efficiency of the antenna but also on the impedance matching network. Here, we focus specifically on nonreconfigurable textile rectennas. The significantly lower power conversion efficiency (PCE) of fully textile-based rectennas compared to rigid counterparts stems from 3 fundamental limitations inherent to flexible substrates [31,32,90]. Firstly, the low dielectric constant of textile materials necessitates larger physical dimensions in impedance matching networks, inevitably increasing conductor losses. Secondly, the nonlinear characteristics of rectifying diodes exhibit greater performance degradation under mechanical deformation. Thirdly, impedance mismatch becomes more pronounced in deformable structures due to dimensional instability.

Early textile-based rectennas often relied on a hybrid architecture that integrated textile antennas with rigid PCB- or FPCB-based rectifiers [95–99], which significantly undermined the key wearable attributes of softness, lightweight, breathability, and flexibility. Monti et al. [90] proposed a fully textile rectenna operating in the 860- to 918-MHz UHF band (Fig. 5A). The device architecture employs a multilayer textile structure bonded by a thermo-adhesive layer, beginning with a rectangular patch antenna with a gain of 4.6 dB as the radiating element and a ground plane that serves as the intermediate layer. The antenna employs a compact design strategy by incorporating notches at all 4 corners of the rectangular patch, effectively reducing the overall size of the low-frequency antenna. The foundation of the system incorporates a full-wave bridge rectifier circuit through the matching of lumped components at the final layer, whose maximum PCE is 50% with an incident power density of 14 μW/cm² at the frequency of 876 MHz. Researchers further optimized textile rectennas by designing antennas, rectifiers, and matching circuits, improving flexible material performance. Wagih et al. [91] proposed a textile rectenna with a maximum PCE of 50% in an energy harvesting system operating at a power density of less than 1 μW/cm². This breakthrough was realized through laser-cut conductive fabric forming a dual-polarized, low-profile patch antenna integrated with FPCB-based multi-frequency rectifiers on a lossy felt substrate. While these designs demonstrate promising energy harvesting capability, the partial reliance on nontextile rectifier components indicates that achieving a fully textile-integrated rectenna remains an important research direction. To solve this problem, Lu’s research group [31] developed a 2.4-GHz circular patch rectenna through precision laser-cut copper fabric transferred onto textile substrates. Figure 5B and C depicts that the rectifying circuit utilizes a first-order Greinacher-type full-wave rectification topology, directly integrating with antenna by stub matching method, demonstrating outstanding performance with an antenna gain of 4.4 dBi and a remarkable PCE reaching 58% at an RF input power of 10 dBm.

Furthermore, to enhance energy harvesting efficiency by expanding the effective reception area of antenna in low-power density environments while simultaneously optimizing impedance matching and frequency response, research on a textile rectenna array with higher gain than a single antenna element has been increasingly prominent in the RF energy harvesting field. As shown in Fig. 5D, Estrada et al. [89] fabricated 4 × 4 and 9 × 9 bowtie-shaped rectenna arrays by screen-printing silver paste on cotton fabric. By integrating rectifying diodes at ¹/₆-wavelength intervals in the gaps between array elements, where the diodes were connected in series along the co-polarized electric field vector to the antenna feed points with each row in parallel to the DC load, the arrays achieved RF energy harvesting with a power density of 4 to 130 μW/cm² across a frequency range of 2 to 5 GHz (Fig. 5E). Testing showed that the impedance matching and radiation gain of the textile-based device remained unaffected even when placed 1 mm away from the skin. Additionally, the design can be expanded to support dual-polarization operation through the strategic placement of additional diodes at selected feed points. Although this study systematically evaluates the performance of integrated textile rectenna arrays in wearable cloths, advancing their practicality for on-body energy harvesting applications, the way of directly connecting the rectifying diode to the antenna element and relying solely on mutual coupling effects between array elements to adjust the input impedance exhibits limitations, as the RF-DC PCE is typically lower than designs incorporating dedicated impedance matching networks. Therefore, Vital et al. [32] demonstrated rectenna arrays that incorporate impedance matching circuits and rectifying circuits. From Fig. 5F, the silver-coated copper strands were embroidered onto the textile substrate according to the designed antenna pattern and circuit structure, with electronic components securely fixed. Each rectenna consists of a single 2.45-GHz patch antenna connected to a T-type matching network and then to a rectifying circuit. As shown in Fig. 5G, the individual rectenna achieved a gain of 6.5 dBi and 70% PCE. To practically test the energy harvesting capability, the fabricated 2 × 3 rectenna array could still harvest 80 μW of DC power when placed 60 cm away from a 500-mW RF source (Fig. 5H). This work not only provides a large-scale fabrication method for subsequent all-textile active RF devices but also demonstrates the rectenna’s capability for long-distance, highly efficient energy harvesting.

Table 1 summarizes representative textile-based RF energy harvesting devices in terms of operating frequency, integration architecture, impedance matching network, rectifier topology, and energy conversion performance. Most reported textile rectennas operate in the sub-GHz industrial, scientific, and medical (ISM) band (0.86 to 0.92 GHz) and the 2.45-GHz ISM band, benefiting from a favorable trade-off between propagation loss, antenna size, and suitability for wearable applications. Recent studies have further extended textile platforms to multiband and wideband operation, reflecting growing interest in broadband ambient RF energy harvesting. Laser-cut copper fabric antennas are most widely adopted due to their low ohmic loss and fabrication repeatability, whereas embroidered conductive thread antennas provide superior mechanical compliance at the expense of reduced RF efficiency. The choice of rectifier topology is strongly dependent on the input power level and system requirements. Voltage doubler rectifiers are typically employed under ultra-low input power conditions to achieve higher DC output voltage, while single-diode half-wave rectifiers offer the highest RF-to-DC conversion efficiency at moderate power levels owing to their low conduction loss and simple structure. Full-wave bridge rectifiers are more suitable for higher input power scenarios, particularly when polarization or phase insensitivity and low output voltage ripple are required, albeit with increased diode loss. For multiband energy harvesting, parallel rectifying branches optimized for different frequency bands are commonly implemented to enable efficient multi-frequency rectification. It should be noted that energy harvesting efficiency is characterized using different metrics across the literature. Textile metasurfaces and antenna arrays often report overall system harvesting efficiency, whereas rectennas typically evaluate RF-to-DC PCE of the rectifier. Therefore, careful distinction is required when comparing reported efficiency values.